Clean up AttachmentContentTypeValidator conditions

lib/paperclip/validators/attachment_content_type_validator.rb

@@ -6,14 +6,12 @@ module Paperclip
         value = record.send(:read_attribute_for_validation, attribute)
         allowed_types = [options[:content_type]].flatten
 
-        if value.present? 
-          unless allowed_types.any? { |type| type === value }
+        if value.present? && allowed_types.none? { |type| type === value }
           record.errors.add(attribute, :invalid, options.merge(
             :types => allowed_types.join(', ')
           ))
         end
       end
-      end
 
       def check_validity!
         unless options.has_key?(:content_type)